PAC International RSIC-SI-1 ULTRA
RSIC-SI-1 ULTRA is a heavy-duty resilient isolation clip engineered to decouple walls and ceilings, cutting structure-borne vibration and boosting STC/IIC performance. Its factory-tuned steel spring, elastomer damping, and hat-channel mount deliver repeatable results across multifamily, studio, office, and healthcare projects where noise control, privacy, and comfort are priorities.
- High Isolation Performance: Robust spring-and-rubber design breaks the vibration path, reducing structure-borne transmission and improving real-world STC/IIC in ceiling systems.
- Heavy-Duty Capacity: Engineered for higher loads with multi-layer gypsum — supports dense acoustic assemblies without sagging.
- Versatile Applications: Ideal for multifamily, studios, offices, schools, and healthcare — anywhere noise control, privacy, and comfort matter.
- Consistent, Repeatable Results: Factory-tuned isolation element reduces installer variability compared with ad-hoc decoupling methods.
- Durable Construction: Corrosion-resistant hardware and resilient elastomer maintain isolation under long-term compression, temperature swings, and building movement.
Online orders up to 4,999 pieces. For anything larger, call (415) 864-4440 and we'll price the project with you.
Volume pricing
$69.99 per clip. Order 250+ clips and pay $69.59 per clip — an extra $0.40 off per clip for each additional 250 clips, down to a $67.28 per clip floor.
Discounts apply automatically in the cart and count boxes and cases toward the total.
RSIC-SI-1 ULTRA Specifications
- Width
- 3-5/8 in
- Height
- 9-1/6 in
- Depth
- 4-7/8 in
- Max spacing
- 24 in × 48 in on-center
- Max load
- 5 / 10 / 20 / 40 lb (spring color coded)
Hat channel specs
- Gauge
- 25 gauge (hemmed edge)
- Depth
- 7/8 in
- Width — top
- 1 1/4 in
- Width — bottom
- 2 1/2 in
RSIC-SI-1 ULTRA Project Calculator
Enter your surface square footage. We'll return a clip, channel, and screw count for your project — calculations run on our servers so estimates stay accurate as our field data improves.
Adds MLV over Good for a denser limp-mass layer.
Estimated STC — Planning use only
This value is an approximate assembly projection, not a project-specific assessment, certified laboratory test result or performance guarantee. Actual performance varies with the complete assembly, installation, flanking paths, penetrations and site conditions.
Estimates follow PAC's ULTRA layout with 24" channel and 48" clip spacing.
Estimated STC Gauge
Compare how the RSIC-SI-1 ULTRA performs across assembly tiers. Select an assembly below to see the estimated STC score.
RSIC-SI-1 ULTRA + hat channel + double 5/8" drywall + Green Glue on insulated joists.
Estimated STC — Planning use only
This value is an approximate assembly projection, not a project-specific assessment, certified laboratory test result or performance guarantee. Actual performance varies with the complete assembly, installation, flanking paths, penetrations and site conditions.
- STC 30-39: Loud speech clearly audible next room.
- STC 40-49: Loud speech muffled — normal residential wall.
- STC 50-59: Loud speech barely audible; suitable for offices & multi-family.
- STC 60+: Approaches studio-grade isolation.
How RSIC-SI-1 ULTRA compares
| Model | Primary Use | Isolation Element | Typical Layout | Notes |
|---|---|---|---|---|
| RSIC-SI-1 ULTRAthis | High-load wall/ceiling decoupling | Steel spring + elastomer | ≤24" channel · ≤48" clip o.c. | Best low-frequency control |
| RSIC-1 | General wall/ceiling decoupling | Elastomer | ≤24" · ≤48" | Popular all-around |
| RSIC-2 | Heavy ceilings | Elastomer (dual-deflection) | Project-specific | Dual-deflection design |
Applicable Assemblies
See where the RSIC-SI-1 ULTRA fits — from budget baseline to studio-grade isolation.
Best — RSIC-SI-1 ULTRA + Double Drywall + Green Glue + Insulation
Joists · Rockwool insulation · RSIC-SI-1 ULTRA + hat channel · 5/8" drywall · Green Glue · 5/8" drywall · acoustic sealant.
Better — RSIC-SI-1 ULTRA + Double Drywall + Green Glue
Joists · Rockwool insulation · RSIC-SI-1 ULTRA + hat channel · 5/8" drywall · Green Glue · 5/8" drywall.
Good — RSIC-SI-1 ULTRA + Silent FX Drywall
Joists · Rockwool insulation · RSIC-SI-1 ULTRA + hat channel · Silent FX damped drywall.
